waves and vibrations

waves and vibrations

1. type of waves

   • mechanical waves
     • sound waves
     • seismic waves
     • waves that pass through a substance are vibrations that pass through the substance
   • electromagnetic waves
     • vibrating magnetic and electric fields that progress through space without the need for a substance
     • the spectrum

2. longitudinal waves

   • waves in which the direction of vibration of the particle is parallel to the direction in which the wave travels
   • rarefaction
     • expansion

3. transverse waves

   • waves in which the direction of vibration is perpendicular to the direction in which the travels
   • electromagnetic waves
   • secondary seismic waves

4. polarisation

   • plane-polarised
     • when the vibrations stay in one place only
   • unpolarised
     • if the vibrations change from one place to another
   • plane of polarisation
     • EM waves
       • the plane in which the electric field oscillates
   • if unpolarised light is passed through two polaroid filters
     • the intensity changes if one polaroid is turned relative to the other one
     • polarised light from the first filter will not be able to enter the second filter
       • alignment of the molecules in the second is at 90⁰

5. polaroid sunglasses

   • reduce the glare of light reflected by water or glass